<template>
  <div class="pagination">
    <button :disabled="pageNo==1" @click="$emit('getPage',pageNo-1)">上一页</button>
    <button v-if="startPageAndEndPage.start>1" @click="$emit('getPage',1)" :class="{active:pageNo==1}">1</button>
    <button v-if="startPageAndEndPage.start>2">···</button>

    <button v-for="(page,index) in startPageAndEndPage.end" :key="index" v-show ="page>=startPageAndEndPage.start" @click="$emit('getPage',page)" :class="{active:pageNo==page}">{{page}}</button>

    <button v-if="startPageAndEndPage.end<totalpage-1">···</button>
    <button v-if="startPageAndEndPage.end<totalpage" @click="$emit('getPage',totalpage)" :class="{active:pageNo==totalpage}">{{totalpage}}</button>
    <button :disabled="pageNo==totalpage" @click="$emit('getPage',pageNo+1)">下一页</button>

    <button style="margin-left: 30px">共 {{total}} 条</button>
  </div>
</template>
  
  <script>
export default {
  name: "Pagination",
  // pageNo 当前页码数   pageSize 每页有多少数据 total 总共多少条数据 continue 连续页个数
  props: ["pageNo", "pageSize", "total", "continues"],
  computed: {
    //总共多少页
    totalpage() {
      //向上取整
      return Math.ceil(this.total / this.pageSize);
    },
    //计算连续页数起始页和结束页
    startPageAndEndPage() {
      const { pageNo, totalpage, continues } = this;
      //定义起始和结束数字
      let start = 0,
        end = 0;
      if (continues >= totalpage) {
        start = 1;
        end = totalpage;
      } else {
        start = pageNo - parseInt(continues / 2);
        end = pageNo + parseInt(continues / 2);}
        //pageNO为1 2时 和 最后两页时候特殊情况
        if (start < 1) {
          start = 1;
          end = continues;
        }
        if (end > totalpage) {start = totalpage - continues + 1;
        end = totalpage;}
      
      return { start, end };
    },
  },
};
</script>
  
  <style lang="less" scoped>
.pagination {
  text-align: center;
  button {
    margin: 0 5px;
    background-color: #f4f4f5;
    color: #606266;
    outline: none;
    border-radius: 2px;
    padding: 0 4px;
    vertical-align: top;
    display: inline-block;
    font-size: 13px;
    min-width: 35.5px;
    height: 28px;
    line-height: 28px;
    cursor: pointer;
    box-sizing: border-box;
    text-align: center;
    border: 0;

    &[disabled] {
      color: #c0c4cc;
      cursor: not-allowed;
    }

    &.active {
      cursor: not-allowed;
      background-color: #409eff;
      color: #fff;
    }

  }
}
.active{
      background-color: skyblue;
    }
</style>
  